[PATCH v4 2/3] mf: Fix computing fastest and slowest rates for the media session.

[Giovanni Mascellani]

The current algorithm correctly only considers the absolute value of
nodes' rates when computing maximum and minimum, but omits negating
the result when in reverse direction.

Also, when computing the minimum intializing with zero is wrong, as
it would always give final result zero. We have to initialize with a
number that is bigger than at least one operand, e.g. FLT_MAX.

Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
---
 dlls/mf/session.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/dlls/mf/session.c b/dlls/mf/session.c
index 925a8c93d20..275b1e3dd98 100644
--- a/dlls/mf/session.c
+++ b/dlls/mf/session.c
@@ -18,6 +18,7 @@
 
 #include <stdarg.h>
 #include <math.h>
+#include <float.h>
 
 #define COBJMACROS
 
@@ -3532,7 +3533,7 @@ static HRESULT session_get_presentation_rate(struct media_session *session, MFRA
     struct media_sink *sink;
     HRESULT hr = E_POINTER;
 
-    *result = 0.0f;
+    *result = fastest ? FLT_MAX : 0.0f;
 
     EnterCriticalSection(&session->cs);
 
@@ -3556,6 +3557,9 @@ static HRESULT session_get_presentation_rate(struct media_session *session, MFRA
 
     LeaveCriticalSection(&session->cs);
 
+    if (direction == MFRATE_REVERSE)
+        *result = -*result;
+
     return hr;
 }
 
-- 
2.32.0.rc0